OS/2 Boot Logo

File Format
Name	OS/2 Boot Logo
Ontology	Electronic File Formats Graphics OS/2 Boot Logo
Extension(s)	(none), .lgo
Released	1994

OS/2 Boot Logo is a compressed raster graphics format used for the logo shown when OS/2 Warp operating systems boot. Images are 640×400 (Warp 3), or 640×480 (Warp 4), with 16 colors.

The file used by the operating system is named "OS2LOGO", with no filename extension. Inactive logo files are conventionally given the extension .lgo.

Format details

The image data is separated into four bit-planes, each of which is compressed with the EXEPACK2 scheme.

The file begins with a 32-byte header of 8 four-byte integers: the file offset of plane 0, the length of plane 0, the offset of plane 1, the length of plane 1, and so on.

This is the VGA palette used by GBM:

#000000,#000080,#008000,#008080,#800000,#800080,#808000,#808080,
#cccccc,#0000ff,#00ff00,#00ffff,#ff0000,#ff00ff,#ffff00,#ffffff

Software

• PMView Pro
• PrepLogo (OS/2 software; write-only)
• MAKELOGO - A utility on the IBM OS/2 Developer Connection CDs, which can create a logo file from raw bitmap files
• GBM → GBMLOGO (write-only; requires MAKELOGO)
• BMP2LOGO.ZIP (OS/2 software; write-only; requires MAKELOGO)
• [1] → lgoproc
• Deark

Sample files

• PrepLogo → logos.zip
  • WARPLOGO.ZIP - Older version of the above?
• http://www.altsan.org/os2/graphics/index.html
• os2logo
• dexvert samples — image/os2BootLogo